1. Field of the Invention
This invention relates generally to the field of battery charging devices, and more particularly to those battery charging devices that also supply power to additional electrical loads.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems, and portable systems.
Portable information handling systems may be powered by an AC/DC power adapter (hereinafter “AC adapter”) and/or a battery. In order to receive power from the battery, however, it must be sufficiently charged. Currently, battery chargers exist within portable information handling systems which are capable of charging a battery whether or not the information handling system is in use. For example, if the information handling system is coupled to an AC adapter but turned off, then the power from the AC adapter may be used to charge the battery. Additionally, if the information handling system is in use and coupled to an AC adapter, the battery charger may channel excess power not being used by the information handling system to charge the battery. This dynamic charging capability is achieved by setting a static maximum limit for the current capacity of the AC adapter (i.e. the power rating of the AC adapter) within the battery charger and measuring the current used by the system. Any difference between the system current and the static maximum current is then channeled to charge the batteries.
However, this method of dynamic charging works only for systems having fixed wattage AC adapters with known maximum current capabilities. If the portable information handling system that is being powered by the battery is capable of operating with more than a single, fixed wattage AC adapter, it is possible that too much current may be drawn from a lower rated AC adapter if the static maximum limit set in the battery charger does not accurately reflect the true power capabilities of the AC adapter. This scenario may lead to AC-DC latch off and possible data loss.
A similar problem may result when the information handling system is running in a high current demand mode in which the system takes a large percentage of the AC adapter's rated power. In such a case, the AC adapter may try to source more current than it is rated for. This may lead to heating of the AC adapter which may result in AC-DC latch off and possible data loss.
Additionally, vendors may provide portable information handling systems with each having different computing capabilities and current demands. In order to provide power to the systems in a way that is cost effective to both the buyer and the vendor, the vendor may supply only a few adapters for use with the systems. Unfortunately, not all power adapters may be used safely with the information handling systems since each system may have a different static max current setting.
For the foregoing reasons, there is a need for a method and apparatus to dynamically detect the type of AC adapter coupled to an information handling system and then adjust the battery charging current so that it is maximized.